It is well known to investigate samples present inside an environmental chamber, (eg. a vacuum chamber or a chamber filled with a gas), by causing the ellipsometer or the like system to be entirely present outside said environmental chamber, so that an electromagnetic beam generated by a polarization state generator is directed to pass through a first transparent window in said environmental chamber, interact with said sample therewithin, then pass through a second transparent window in said environmental chamber and enter the polarization state analyzer, which passes the electromagnetic beam to a detector thereof. Such a system is described in U.S. Pat. No. 7,253,900 to Woollam et al., for instance. Problems exist when said approach is practiced, however, in that the structure of an environmental chamber can prevent placing polarization state generator and polarization state analyzer components close to a sample under investigation. This can limit the ability to effect an intended, (eg. small and circular), beam spot at the sample location. To provide better proximity of polarization state generator and polarization state analyzer components to a sample under investigation it would be beneficial to be able to place at least some of an ellipsometer or the like components inside an environmental chamber. Beam directing optics can be placed inside an environmental chamber, (see U.S. Pat. No. 5,929,995), to overcome some inherent problems, but this is sometimes not sufficient to provide an electromagnetic beam spot of a certain size and shape onto a sample inside said environmental chamber. Placing polarization state generator and polarization state analyzer components inside an environmental chamber very near an investigated sample can aid with achieving more optimum results in this regard. Therefore, it would be of value to be able to place actual ellipsometer polarization state generator and polarization state analyzer components inside an environmental chamber. Doing so, however, can subject polarization state generator and polarization state analyzer components to, for instance, a vacuum or a gas, and such can be detrimental to their operation. Further, the presence of said components in an environmental chamber can prevent vacuum formation by outgassing.
It is disclosed that the J.A. Woollam Co. has previously obtained many Patents for ellipsometer and the like systems applied with environmental chambers. See for example U.S. Pat. Nos. 5,929,995, 6,636,309, 6,940,595, 6,982,792, 7,030,982, 7,158,231, 7,193,708, 7,209,234, 7,274,450, 7,253,900, 7,283,234, 7,336,361, 7,426,030 and 7,746,471. In particular, the 231 patent discloses placing an entire ellipsometer system inside an environmental chamber in FIGS. 1d, 3 and 5a, and the 792 patent indicates a similar scenario in FIG. 1b. The present invention is distinguished in that, while ellipsometer system polarization state generator and polarization state detector components are contained within an environmental chamber, they are present in encasements that provide components therewithin with an atmosphere that is conducive to their optimum operation. Also, the present invention preferably maintains the source and detector of electromagnetic radiation outside the environmental chamber and provides access via port couplers.
Additional known Patents, not believed to be particularly relevant, are: U.S. Pat. Nos. 8,248,606; 8,054,453; 8,014,000; 7,633,625; 7,616,319; 7,394,551; 7,336,361; 7,304,713; 7,253,900; 7,158,231 and 7,026,626.
Need remains for an ellipsometer system, at least some of the components of which can be placed in an environmental chamber while protecting said components against the effects of, for instance, a vacuum environment.